Inclined or oblique roll mills, sometimes also called inclined twin rolling mill, double roller controlling mill or Mannesmann-type roll mill have been used for many years, in particular, for the production of seamless steel pipes. The apparatus has been continuously improved and developed and the present state of the art is represented by German Pat. No. 21 56 595. The roll stand of the apparatus disclosed in said patent is provided with two-high rolls which are positioned one above the other and with laterally arranged guide disks which can be swung out and are adjustable. The rolls are adjustably mounted in vertical direction in roll frames which are contained in a roll housing. The adjustment of the roll frame is effected by two motor-driven threaded spindles each, which are held, free of play, by a hydraulic retainer cylinder.
The so-called feed angle of the rolls which causes the helical movement of the work piece being rolled is adjustable. For this purpose, the roll frames are developed as drums which can rotate in the stand housing. The feed angle can, in this way, be indefinitely adjusted unless the roll frames are shifted, in a simplified embodiment, by shims. In such a case, the feed angle is not indefinitely adjustable; furthermore, the conversion of the roll stand is time-consuming.
This construction of known two-high inclined-roll mills is disadvantageous since the size of the roll frame requires a roll housing of considerable height which, measured overall, may amount to 8 to 10 meters. Due to the predetermined distance of the roll center above the mill floor, the housing of the rolling mill is placed in a deep foundation pit. As a result, the conduits for leading away the cooling water must also be arranged far below the mill floor. Since a internal tool such as a piercing mandrel or the like, is in most cases, used during the inclined-rolling process, this tool being supported in a thrust bearing via a mandrel support bar, the forces of reaction occurring in this connection must be absorbed by the relatively tall housing columns, which leads to considerable bending thereof.
Furthermore, due to the large size of the mill housing, stretching of the housing columns resulting from the rolling forces must be expected, which increases the roll nip and renders the dimensions of the work pieces being rolled non-uniform.
The dimensioning of the housing of the roll mill and the use of the roll frames furthermore result in a complicated and expensive removal of the rolls, prior to which heavy stand covers and window flaps must be loosened, swung away or completely removed in order to gain access to the roll frames. For this, a crane or a separate change apparatus is required; the removal is time-consuming and mechanically expensive.
Proceeding from the state of the prior art and the disadvantages described above, an object of the present invention is to create a two-high inclined-roll mill which does not have the disadvantages described above and, while of low constructural height and low lengthening, enables a simple and rapid change of rolls or stands at only slight mechanical expense.